Just how small is the smallest machined hole?
A Japanese company says its 0.00044 in. (diameter). Machine-tool maker Makino machined a communications/fiberoptic part on its Edge2 Sinker EDM using a 0.00024-in.-diameter silver-tungsten electrode. A total of eight holes were machined in 2 min and 40 sec. It took 20 sec to machine each hole, with 40% wear to the single electrode. Hole diameters were held to ±0.00005 in. with positioning pitch location accuracy of ±0.0005 in. Positioning pitch between holes was 0.004 in., and the thickness at the hole location was 0.0010 in. The company says its machine produces consistent hole size and location to within 0.002-mm repeatability.